Steering Bearings

Hello,
Does anyone know the OD of the Steering bearings on a 1978 390WR?
I am ordering bearings to attemt to put a different front end on..

Thanks for any help

Are they Timkin or Ball bearings if there Timkin there should be A number on them. Early 78 frames had ball bearings.

Bill
I dont know yet, i was going to order the bearings and then take it apart..
Ill get it apart and See..
Thank You

I have just fitted new ones to my 1980 frame, and I assume they are the same. Here are the dimensions in millimeters:

Dimensions - d (inside diameter) 25.4mm
Dimensions - D (outside diameter) 50.292mm
Dimensions - B (width) 16.130mm

The bearing reference is L44600LA. Here is a link to a supplier in the UK, useful for the dimensions etc:

http://www.bearing-king.co.uk/bearing/l44600la-l44643l-l44610-timken-sealed-type/5781

If it has a black cup on the bottom of the steering head it has Ball bearings.

Bill,
I think the Auto's and 125cc's were the only bikes that still used ball bearings for 1978. All others got the tapered roller bearings.

Your probably right,I remember that my 78 250CR had the Timkens but that was a long time ago. All I have seen lately have been my friends Autos I think they used all the ball bearing frames up for them and then they called the Timken frames 79s till they came out with the actual new 79 frame.

For the tapered roller ones depending on where you go you might have to get the race seperately and they are an inch series bearing not a metric series one I am almost positive.